1. Field of the Invention
The invention is directed to an improved apparatus for pumping fuel from a tank to an internal combustion engine of a motor vehicle in which a pumping assembly is disposed in an impoundment container in the vehicle fuel tank.
2. Description of the Prior Art
One fuel pumping apparatus of the type with which this invention is concerned is known from German Patent Disclosure DE 3942 312 A1. That apparatus has an impoundment container, disposed in the tank, in which a pumping assembly that pumps fuel to the engine is disposed. The apparatus has a jet pump, which is supplied with some of the fuel pumped by the pumping assembly and pumps the fuel out of the tank into the impoundment container. In the process, the portion of the fuel pumped by the pumping assembly that is not consumed by the engine and is returned to the tank is delivered to the jet pump. Near a bottom of the impoundment container, there is a suction chamber, from which the pumping assembly aspirates fuel. When the impoundment container is full, the suction chamber communicates with it via a valve assembly and is disconnected from the tank, so that the pumping assembly aspirates fuel from the impoundment container. When the impoundment container is empty, the suction chamber communicates with the tank through the valve assembly and is disconnected from the impoundment container, so that the pumping assembly aspirates fuel from the tank. An empty impoundment container exists if the tank has been emptied enough that the jet pump cannot pump any further fuel from it into the impoundment container. If a slight quantity of fuel, for instance from a reserve canister, is then used to replenish the tank, then although the impoundment container is still not full, nevertheless the pumping assembly, controlled by the valve assembly, is capable of aspirating fuel directly from the tank. In this case, however, it should be assured that the pumping assembly can reliably aspirate the fuel from the tank at even the least possible fill level of the fuel. In the known apparatus, the valve assembly is disposed under the pumping assembly, resulting in a large structural height, and the pumping assembly must aspirate the fuel from the tank over a great height, which demands a corresponding pumping height.
The apparatus of the invention has the advantage over the prior art that only the check valve is disposed on the bottom of the impoundment container, and thus the pumping assembly can be disposed near the bottom of the impoundment container and hence near the bottom of the tank, and therefore at even a very slight fill level of the fuel in the tank, fuel can be aspirated from the tank by the pumping assembly over a low pumping height. By disposing the float valve laterally offset from the pumping assembly, a low structural height of the apparatus is attained.